Common easy open end closures for beer and beverage containers have a central or center panel that has a frangible panel (sometimes called a “tear panel,” “opening panel,” or “pour panel”) defined by a score formed on the outer surface, the “consumer side,” of the end closure. Popular “ecology” can ends are designed to provide a way of opening the end by fracturing the scored metal of the panel, while not allowing separation of any parts of the end. For example, the most common such beverage container end has a tear panel that is retained to the end by a non-scored hinge region joining the tear panel to the reminder of the end, with a rivet to attach a leverage tab provided for opening the tear panel. This type of container end, typically called a “stay-on-tab” (“SOT”) end has a tear panel that is defined by an incomplete circular-shaped score, with the non-scored segment serving as the retaining fragment of metal at the hinge-line of the displacement of the tear panel.
The container is typically a drawn and ironed metal can, usually constructed from a thin sheet of aluminum or steel. End closures, or can ends, for such containers are also typically constructed from a cut-edge of thin sheet of aluminum or steel, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion. These ends are formed in the process of first forming a cut-edge of thin metal, forming a blank end from the cut-edge, and converting the blank into an end closure which may be seamed onto a container. Although not presently a popular alternative, such containers and/or ends may be constructed of plastic material, with similar construction of non-detachable parts provided for openability.
One goal of the can end manufacturers is to provide a buckle resistant end. Another goal of the manufacturers of can ends is to reduce the amount of metal in the blank which is provided to form the can end while at the same time maintaining the strength of the end. A number of recent disclosures, including U.S. Pat. Nos. 6,736,283, 6,460,723, 6,516,968, 6,419,110, 6,065,634, 6,848,875, 6,877,941, 6,935,826, 6,561,004, 6,499,622, 6,702,142, and US Publication Nos. 2004/0074911, 2003/0121924, 2004/0238546, 2005/0115976, 2005/0247717, 2005/0252922, 2005/0006395, 2004/0140312, 2003/0173367, 2002/0158071, 2005/0029269, are directed to achieving these goals by altering the angles and/or orientations of the chuck wall.
In addition to the references set forth above, U.S. Pat. No. 4,809,861 describes a can end having a compound radius within a countersink groove. The countersink groove, often referred to as a reinforcing bead, annular reinforcing bead, anti-peaking bead, etc., is a generally has a generally U-shaped configuration, and is designed to increase the buckle strength of the can end. A compound radius structure is described as unequal radii of curvature of the inner and outer annular curved portions at the bottom of the countersink. The '861 patent describes an outer radius of curvature being approximately one half of an inner radius of curvature to produce a buckle resistant can end.
Yet another goal of the manufacturers is to produce a can end that will be resilient when dropped from a height after being seamed to a filled can body. It is believed that the specific compound radius described in U.S. Pat. No. 4,809,861 does not increase resiliency to dropping.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior can ends of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.